1. Field of the Invention
The present invention relates to a recording apparatus. In particular, the present invention relates to a recording apparatus in which a general purpose flexible board is used for a part of a flexible board on which a driving circuit is mounted and which serves as a connecting means for connecting a recording means and a relay board so that the part cost of the connecting means can be suppressed.
2. Description of the Related Art
Conventionally, the printer (recording apparatus) for recording an image on a recording medium, for example, the ink-jet printer has been constructed as follows in order to avoid the pollution with any excessive ink such as the ink mist which is produced when the ink is jetted from nozzles. That is, the driving circuit board for the recording head is arranged at a position separated far from the nozzles of the recording head. The recording head and the driving circuit board have been electrically connected to one another by the aid of the flexible board (U.S. Pat. No. 6,206,507 B1 (corresponding to Japanese Patent Application Laid-open No. 11-165408), for example, FIG. 2).
In recent years, it is contemplated to simplify the structure of the head unit by constructing the head unit by using so-called TAB (tape automated bonding) and/or COF (chip on film) which includes an IC chip mounted as a driving circuit on a flexible board to be connected to the recording head. In the case of COF or the like, the input side wiring of the IC chip is connected to a relay board which is carried on the head unit. The recording data, which is outputted from the control circuit, is inputted into the IC chip via the relay board.
However, in recent years, it is more strictly required that the printing is performed at a high speed with high definition. Therefore, as for the recording head, the number of nozzles is increased, while the nozzle pitch is decreased. Accordingly, the terminal pitch of the recording head and the bump pitch of the IC chip are narrowed. As a result, the wiring density of COF or the like is narrowed, and the processing cost becomes expensive. For theses causes, a problem has arisen such that the product cost becomes more expensive for COF or the like which is originally an expensive part.
On the other hand, the relay board is arranged at the position separated far from the recording head in order to avoid the pollution with the ink. Therefore, the wiring length of COF or the like (product length) is lengthened to connect the relay board and the recording head. Corresponding thereto, a problem has arisen such that the product cost becomes extremely expensive. The product cost of COF or the like is proportional to the entire length thereof. Therefore, even when the length is extended for the input side wiring portion of the IC chip in which the wiring density is more widened, the product cost is equivalent to that of the case in which the output side wiring portion, in which the wiring density is more narrowed, is extended.